There are presently available drivers for threaded fasteners, such as for screws and the like. For example, U.S. Pat. No. 3,392,767 issued July 16, 1968 to George B. Stillwagon, Jr., describes a permanent magnet driver employing an annular band or strip of thickness-oriented magnetized rubber bonded barium ferrite disposed within or in surrounding relation to the driver.
Another prior art device, described in U.S. Pat. No. 3,024,682 issued Mar. 13, 1962 to Lewis C. Finkle, describes a tool or attachment which may be used as a nut runner for tightening nuts and the like.
Another prior art device, described in U.S. Pat. No. 985,087 issued Feb. 21, 1911 to Charles M. Wilson, appears to describe a bit having a free end provided with a recess having a curved wall to accommodate different sizes of screw-eyes.
Another prior art device, described in U.S. Pat. No. 882,937 issued Mar. 24, 1908 to Thomas J. Fegley, appears to describe a screw eye driver having a slotted head (c) for the reception of the eye portion of the screw eye. As can be clearly seen from FIGS. 1, 3, and 7, the circular portion (n) of the screw eye is retained within the slotted head substantially between the upper (not reinforced) bifurcated arm portions of the head portion (c). Thus, with the screw eye being screw into, for example, hard wood, the upper bifurcated arm portions may bend or break.
Other prior art patents of interest are U.S. Pat. No. 2,437,762 issued Mar. 16, 1948 to Louis Simonin and Offenlegungsschrift DE No. 3223109A1.
The obvious disadvantages of these prior art devices are: (1) positive lag alignment is not achieved, (2) the devices do not utilize a reinforcing sleeve over the length of the bifurcated arm, (3) the fastening devices are not securely held to enable driving into hard wood etc., (4) the tools are relatively expensive and/or sumptuous in constituent components.
These patents are mentioned as being representative of the prior art and other pertinent references may exist. None of the above cited patents are deemed to affect the patentability of the present claimed invention.
The present invention involves a novel combination of features combined in such a way to afford a solution to the difficulties and disadvantages of the prior art devices.
For example, in contrast to the prior art, the present invention provides a single purpose tool for flattened end lag screws to facilitate driving into, for example, hard wood etc., while substantially reducing lag wobble. Each tool attachment or lag driver is designed to accommodate a selected sized fastener having a flattened end lag configuration. The lag driver has a hex shank with a circumferential detent to enable utilization in a typical screwgun tool and improved clamping in a drill chuck, a slotted end or bifurcated arm members each with a chamfer on a semicircular notch extending from the free end downwardly a predetermined partial portion of each arm to substantially improve positive alignment of the screw or shank portion of the lag. In addition, a discrete sleeve is force fitted about said bifurcated arm members to reinforce said arm members to substantially prevent spreading or breaking thereof, and to substantially prevent lag slippage, thereby, enabling driving the lag into hard wood etc. without pre-drilling. The present invention provides a device having a robust and relatively inexpensive structure, enables manipulation, is adapted for ease of use and involves a minimum of associated parts.